1. Field of the Invention
The present invention relates to a light emitting diode module, and more particularly, a light emitting diode module which can generate a stable operating current.
2. Description of the Prior Art
Due to their slim shapes, low power consumption and low radiation, liquid crystal displays (LCDs) are widely applied in electronic devices such as notebooks, monitors, and PDAs (personal digital assistants). Besides, the organic light emitting diode (OLED) display can be operated without a backlight source and color filters, and has a slimmer shape and better performance in color, thus the OLED display is also widely used.
However, in a pixel driving circuit of an OLED display of prior art, switch components used to control an operating current and the brightness of a light emitting diode are a source of instability. For example, the threshold voltage of a transistor is often biased after operating for along time, altering the current flowing through the light emitting diode and resulting in emitting an erroneous grey level. Besides, as the size of the display increases, the voltage drop from the voltage source deteriorates. This adds to the aging issue and worsens the instability of current flows and display quality.
Although there are some ways developed to compensate the threshold voltage bias, those methods lead to an increased number of switches and/or capacitors, lowering an aperture ratio of the display, and increasing the difficulty to design a driving circuit of a high resolution display.